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Submission #441713

# Submission time Handle Problem Language Result Execution time Memory
441713 2021-07-05T21:27:03 Z JovanB The Xana coup (BOI21_xanadu) C++17
0 / 100
 70 ms 19952 KB 
#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using ld = long double;

const int MAXN = 100000;

int dp[MAXN+5][2][2];

int dpp[MAXN+5][2][2];
int ndpp[2][2];
int col[MAXN+5];

vector <int> graf[MAXN+5];

void dfs(int v, int p){
    bool leaf = 1;
    for(int j=0; j<2; j++) for(int k=0; k<2; k++) dpp[v][j][k] = MAXN;
    dpp[v][0][0] = 0;
    dpp[v][1][0] = 0;
    for(auto c : graf[v]){
        if(c != p){
            dfs(c, v);
            leaf = 0;
            for(int j=0; j<2; j++) for(int k=0; k<2; k++) ndpp[j][k] = MAXN;
            for(int j=0; j<2; j++){
                for(int k=0; k<2; k++){
                    ndpp[j][k] = min(ndpp[j][k], dpp[v][j][k] + dp[c][j][0]);
                    ndpp[j][k] = min(ndpp[j][k], dpp[v][j][1^k] + dp[c][j][1]);
                }
            }
            for(int j=0; j<2; j++) for(int k=0; k<2; k++) dpp[v][j][k] = ndpp[j][k];
        }
    }
    if(leaf){
        dp[v][col[v]][1] = MAXN;
        dp[v][1^col[v]][0] = MAXN;
        dp[v][1^col[v]][1] = 1;
        return;
    }
    dp[v][col[v]][0] = dpp[v][1][0];
    dp[v][1^col[v]][0] = dpp[v][1][1];
    dp[v][1^col[v]][1] = 1 + dpp[v][0][0];
    dp[v][col[v]][1] = 1 + dpp[v][0][1];
}

int main(){
    ios_base::sync_with_stdio(false), cin.tie(0);
    cout.precision(10);
    cout << fixed;

    int n;
    cin >> n;
    for(int i=1; i<n; i++){
        int a, b;
        cin >> a >> b;
        graf[a].push_back(b);
        graf[b].push_back(a);
    }
    for(int i=1; i<=n; i++){
        cin >> col[i];
        col[i] ^= 1;
    }
    dfs(1, 0);
    int res = min(dp[1][1][0], dp[1][1][1]);
    if(res >= MAXN) cout << "Impossible\n";
    else cout << res << "\n";
    return 0;
}

Subtask #1
0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 2 ms 2636 KB Output is correct
3 Correct 3 ms 2636 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Incorrect 2 ms 2636 KB Output isn't correct

Subtask #2
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 2 ms 2636 KB Output is correct
3 Correct 3 ms 2636 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Incorrect 2 ms 2636 KB Output isn't correct

Subtask #3
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 70 ms 19872 KB Output is correct
2 Incorrect 62 ms 19656 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #4
0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 63 ms 19952 KB Output is correct
2 Incorrect 64 ms 19728 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #5
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 2 ms 2636 KB Output is correct
3 Correct 3 ms 2636 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Incorrect 2 ms 2636 KB Output isn't correct